1. Field
Embodiments of the present disclosure generally relate to apparatus and methods for processing semiconductor substrates. More particularly, embodiments of the present disclosure relate to apparatus and method for shielding magnetic noises from plasma generated in a semiconductor substrate processing chamber.
2. Description of the Related Art
Processing chambers used in semiconductor processing generally have inherent non-uniformities of varying degrees depending on chamber structure and processing conditions. The inherent non-uniformities generally cause skews, which can be compensated by hardware or software adjustment. However, the skew caused by inherent non-uniformity of hardware sometimes overlays with non-uniformity cause by external factors, such as magnetic field of the earth, thermal and or magnetic field of surrounding processing chambers. The overlaid non-uniformities are difficult to compensate or adjust because the external factors may be random and difficult to predict.
Therefore, there is a need for apparatus and methods for reducing and compensating skews caused by both inherent non-uniformities and external factors.
Embodiments of the present disclosure generally provide apparatus and method for improving processing uniformity by reducing external magnetic noises.
One embodiment of the present disclosure provides an apparatus for processing semiconductor substrates. The apparatus includes a chamber body defining a vacuum volume for processing one or more substrate therein, and a shield assembly for shielding magnetic flux from the chamber body disposed outside the chamber body, wherein the shield assembly comprises a bottom plate disposed between the chamber body and the ground to shield magnetic flux from the earth.
Another embodiment of the present disclosure provides a method for processing a substrate. The method includes applying a shield between a processing chamber and the ground to shield the processing chamber from magnetic flux generated by the earth, measuring a process rate of a process recipe performed by the processing chamber, and determining a skew in the measured process rate. The method further includes adjusting one or more components of the processing chamber or one or more processing parameters according to the determined skew, and processing one or more substrates in the processing chamber.
Yet another embodiment of the present disclosure provides a method for processing a substrate. The method includes applying a shield around a processing chamber to shield the processing chamber from magnetic flux and measuring a processing rate of the processing chamber to obtain a skew, and adjusting one or more components of the processing chamber or one or more processing parameters to correct the skew. The method further includes etching a template mask disposed below a patterned mask to form both a narrow feature and a wide feature in the template mask, removing the patterned mask from the narrow feature while substantially retaining the patterned mask on the wide feature, and etching the template mask to thin the exposed narrow feature relative to the wide feature formed in the template mask.
So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.
Embodiments of the present disclosure provide apparatus and methods for improving processing uniformity in a semiconductor processing chamber, such as a plasma processing chamber. According to embodiments of the present disclosure, a shield assembly including a bottom plate positioned between a processing chamber and the ground may be applied to the processing chamber. The bottom plate attenuates or even eliminates magnetic flux from the earth. The shield assembly may also include a top plate and sidewalls. The top plate, sidewalls and bottom plate form an enclosure where the processing chamber is positioned. By enclosing the processing chamber, the shield assembly effectively preventing environment magnetic flux from entering the processing volume of the processing chamber.
According to one embodiment of the present disclosure, processing rate may be measured and a skew determined while the shield assembly is applied around the processing chamber. With the environment magnetic flux substantially shielded by the shield assembly, the measured skew substantially represents non-uniformities that are inherent to the processing chamber, thus, can be compensated by adjusting one or more components of the processing chamber or adjusting one or more processing parameters. In one embodiment, one or more coils of an antenna assembly for generating a plasma inside the processing chamber may be adjusted to adjust plasma distribution, thus, compensate the skew. In another embodiment, upon compensation of the skew inherent to the processing chamber, processing uniformity may be improved. The improved uniformity may also enable adjustment of processing parameters, such as plasma bias voltage, to achieve processing effects that cannot be otherwise achieved.
The chamber body 130 defines a processing volume 132. A substrate support 132 is disposed in the processing volume 132 for supporting a substrate 101 to be processed in the processing volume 132. A vacuum pump 138 may be coupled to the chamber body 130 to maintain a vacuum environment in the processing volume 132. A gas source 134 may be coupled to a gas distribution assembly 136. The gas distribution assembly 136 delivers one or more processing gas from the gas source 134 to the processing volume 132.
The plasma generator 120 generates plasma in the processing volume 132 for processing the substrate 101. In one embodiment, the plasma generator 120 may include an antenna assembly 150 for generating inductively coupled plasma in the processing volume 132. The antenna assembly 150 may include two antennas 154, 156 positioned above the chamber body 130. The antennas 154, 156 may be attached to a frame 152 by brackets 158. The antennas 154, 156 may be connected to a radio frequency (RF) power source 168 via a matching network 164 for plasma generation. In one embodiment, the antenna assembly 150 may include one or more motors 162 for adjusting the coils 154, 156 relative to the processing volume 132. The one or more motors 162 may also be used to adjust relative position of the coils 154, 156. In one embodiment, the motors 162 may be attached to the frame 152. Optionally, a shield 160 may be positioned around the antennas 154, 156.
The shield assembly 110 shields the processing volume 132 from external magnetic flux. Particularly, the shield assembly 110 includes one or more components positioned between the chamber body 130 and the ground 102 to shield any magnetic flux from the earth. In one embodiment, the shield assembly 110 may include a top plate 112, sidewalls 114 and a bottom plate 116. The top plate 112, sidewalls 114 and bottom plate 116 define an enclosure 146 to enclose the chamber body 130 therein. In one embodiment, the plasma generator 120 is also enclosed in the shield assembly 110. The bottom plate 114 positioned between the chamber body 130 and the ground 102 effectively attenuates magnetic flux from the earth, which may affect plasma distribution within the processing volume 132. Beside the magnetic flux from the earth, the shield assembly 110 also attenuates other environmental magnetic noises, such as noises from adjacent processing chambers, from entering the processing volume 132.
The shield assembly 110 may be formed from any material that is capable of attenuate magnetic flux from the environment. In one embodiment, the shield assembly 110 may be formed from a metal having high magnetic permeability and capable of shielding against static or low frequency magnetic fields. For example, the shield assembly 110 may be formed from stainless steel, such as 410 stainless steel, mu-metal, or soft-iron.
The shield assembly 110 may be formed in any suitable shape to enclose the chamber body 130 and the plasma generator 120 therein and to accommodate surroundings of the processing chamber 100. Sectional view of the sidewalls 114 may be circular or polygonal, such as rectangular or hexagonal.
The processing chamber further includes a controller 170 for monitoring and controlling the process performed therein. The shield assembly 110 allows the processing chamber 100 to process substrates with minimal affect from the environment. The controller 170 may connect and control the RF power source 168, a bias power source 144 via a matching network 142, or the motor 162. In one embodiment, the controller 170 may be used to monitor the processing rate across the substrate with the shield assembly 110 applied around the chamber body 130 and the plasma generation. The controller 170 may include a control program that determines a skew from the monitored process rate, and generates control signals to components of the processing chamber 100 to adjust the process rate and improve uniformity across the substrate.
Box 182 of the method 180 includes applying a shield around a processing chamber to shield the processing chamber from external magnetic flux. In one embodiment, the shield includes a plate disposed between the processing chamber and the ground to block any magnetic flux from the earth. The shield may be similar to the shield assembly 110 of the processing chamber 100.
Box 184 of the method 180 includes measuring a process rate across a substrate while running a process in the processing chamber having the shield applied. Since the shield effectively substantially prevents environmental magnetic noises from entering the processing chamber, non-uniformities in the measured process rate can be contributed substantially to causes inherent to the processing chamber itself, thus, may be addressed by adjusting the processing chamber alone. The measurement of box 184 may be performed in-situ using sensors in the processing chamber, such as the processing chamber 100. Alternatively, the measurement of box 184 may be performed in a metrology station independent from the processing chamber.
Box 186 of the method 180 includes characterizing the measured process rate. Characterizing the measured process rate may include a calculation to determine one or more characters of the measured process rate so that adjustment can be made to obtain desired process rate based on the one or more characters. In one embodiment, charactering the measured process may be determining a skew that reflects gradients of the non-uniformities in the measured process rate. In one embodiment, the skew may be used to generate signals for adjusting a plasma generator. Other characters of the measured process rate may be used according to process requirement.
Box 188 of the method 180 includes adjusting one or more components of the processing chamber or one or more processing parameters according to the one or more characters determined in box 186. The adjustment of box 188 may be used to improve processing results, such as improving uniformity across the substrate being processed, or achieving certain process results, such as edge thin or edge thick. In one embodiment, a plasma generator of the processing chamber may be adjusted according to the direction of the skew in the measured process rate to improve uniformity. For example, the plasma generator 120 in the processing chamber 100 may be adjusted by the controller 170. The plasma generator 120 may be adjusted by various approaches, such as adjusting positions of the antennas 154, 156 relative to the processing volume 132, adjusting relative positions between the antennas 154, 156, adjusting frequency, phase, or amplitude of the RF power source 168, or combinations thereof. In one embodiment, the positions of the antennas 154, 156 may be adjusted by moving the motors 162. Alternatively, other chamber components or processing parameters may be adjusted. For example, a bias power applied to the plasma may be adjusted. In the processing chamber 100, bias voltage applied to the substrate 101 by the bias power source 144 may be adjusted to improve process uniformity. For example, the bias voltage may be increased to allow lower plasma density in the processing volume 132, thus, improving controllability of the process rate across the substrate.
Box 190 of the method 190 includes processing one or more substrates in the processing chamber after adjustment with improved results. Generally, the same process recipe as performed in box 184 may be run for plurality of substrates for production with improved results. The process recipe may be any suitable ones such as etching, deposition, or epitaxial growth.
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The etch processes described in
Box 310 of the method 300 includes applying a shield around a processing chamber and measuring a processing rate of the processing chamber to obtain a skew. The shield is similar to the shield assembly 110 of the processing chamber 100 that prevents environmental magnetic flux from entering the processing chamber. The shield may include a top plate, sidewalls and a bottom plate to enclose the processing chamber therein. In one embodiment, a processing rate may be measured and a skew determined to non-uniformity after excluding the external magnetic noises from the processing chamber.
Box 320 of the method 300 includes adjusting one or more components of the processing chamber or processing parameters to correct the skew. Similar to box 188 of the method 180, chamber components, such as antennas in a plasma generator, or processing parameters, such as bias voltage, may be adjusted to correct the skew and improve uniformity.
Depending on the number of processing chambers used, box 310 and box 320 may be performed for some or all the processing chambers used in the processes to follow.
Box 330 of the method 300 includes etching one or more layers in a template mask disposed below a patterned mask to form both a narrow feature and a wide feature in the template mask. The narrow feature may be arranged in a central cell region and the wide feature may be arranged a periphery region.
Box 340 of the method 300 includes removing the patterned mask from the narrow feature while substantially retaining the patterned mask on the wide feature.
Box 350 of the method 300 includes etching the template mask to thin the exposed narrow feature relative to the wide feature formed in the template mask.
Box 360 of the method 300 includes removing the patterned mask from the wide feature and etching through all layers of template mask to expose a spacer layers formed below, as shown in
Box 370 of the method 300 includes forming sidewall spacers around narrow and wide features in the template mask as shown in
Box 380 of the method 300 includes removing the template mask on the narrow feature to form a spacer mask from the sidewall spacers. The pitch of the spacer mask in the central region is almost half of the pitch of the narrow features in the photoresist pattern in box 330.
Box 390 of the method 300 includes etching the spacer layer disposed under the spacer mask to form spacers of a narrow pitch and a wide pitch as shown in
Plot (c) schematically illustrates a skew of etch rate across a substrate for the same tungsten etch in the same plasma chamber as in plots (a) and (b) but with a shield. The shield is formed a mu-metal and structurally similar to the shield assembly as described in
Even though, embodiments of the present disclosure are described in association with inductive coupled plasma chamber used for etching, embodiments of the present disclosure may be used in combination with any processing chambers that use plasma to improve processing uniformities.
While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
This application claims benefit of U.S. Provisional Application Ser. No. 61/757,019 (Attorney Docket No. 20320L), filed Jan. 25, 2013, which is incorporated herein by reference.
Number | Date | Country | |
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61757019 | Jan 2013 | US |